1. Field of the Invention
The present invention relates to a controller for a vehicle which stops an engine mounted in a vehicle when a stop condition holds while the engine is in operation, and then restarts the engine when a start condition holds while the engine is at rest.
2. Description of the Related Art
Hitherto, there has been known a controller for a vehicle adapted to temporarily stop an engine while a vehicle is at rest thereby to restrain fuel consumption from idling while the vehicle is at rest (refer to, for example, Japanese Patent Application Laid-Open No. H4-358729).
In a conventional controller for a vehicle, an engine is stopped when the vehicle speed reaches zero and the vehicle stops and the clutch switch turns off (i.e., when a stop condition holds), and the engine is restarted when a predetermined time has elapsed following the engine stop (i.e., when a start condition holds).
Further, in the conventional controller for a vehicle, the predetermined time, which is an engine start condition, has been set at a fixed time.
Here, when the passenger compartment is being air conditioned from the engine in operation, if the engine is stopped and air conditioning is stopped accordingly, then the temperature in the passenger compartment gradually rises. If the time from the stop to the restart of the engine is fixed, as with the conventional controller for a vehicle, the temperature in the passenger compartment may rapidly rise when, for example, an outside air temperature is high or many passengers are in the passenger compartment, causing the passengers in the passenger compartment to feel uncomfortable by the time the engine is restarted and the air conditioning is resumed.
Further, when a coolant is being circulated in a coolant circulation passage via a radiator of the engine by a pump driven by the engine and the air to be blown out into the passenger compartment through the intermediary of a heat exchanger connected to the coolant circulation passage is being heated to perform heating, if the engine is stopped and the pump is stopped accordingly, then the temperature in the passenger compartment gradually drops.
If the time from the stop to the restart of the engine is fixed, as with the conventional controller for a vehicle, then the temperature in the passenger compartment may rapidly lowers if, for example, an outside air temperature is low, and the passengers in the passenger compartment may feel uncomfortable before the engine is restarted and the heating is resumed.
However, if the stop duration of the engine is set to be shorter so as to prevent the aforesaid inconvenience, then it would be undesirably less effective in restraining fuel consumption while idling.